If It Bends.... give it a bend
I always try to give at least one arm something to do.
Hold something
Fiddle with hair
Hand on hip
Hand or arm on a rail
Hands in pockets with elbows slightly out.
I like to have a bend in the knees. Maybe putting a foot up on a small step, putting the weight on their back leg and slightly bending the front leg.
Give a slight bend forward at the waist.
Play with the bend and angles and get a feel for how they make the image different!
Some will make for an edgier feel and some will give it a softer more romatic feel.